6 Na2S2O3 + 2 I3 → 3 Na2S4O6 + 6 NaI

This is an oxidation-reduction (redox) reaction:

12 SII - 6 e- → 12 S5/2 (oxidation)

6 I0 + 6 e- → 6 I-I (reduction)

Na2S2O3 is a reducing agent, I3 is an oxidizing agent.

Reactants:

  • Na2S2O3
    • Names: Sodium thiosulfate source: wikipedia, accessed: 2019-09-28source: wikidata, accessed: 2019-09-02source: ICSC, accessed: 2019-09-04, Sodium hyposulfite source: wikipedia, accessed: 2019-09-28source: wikidata, accessed: 2019-09-02, Hyposulphite of soda source: wikipedia, accessed: 2019-09-28
    • Appearance: White crystals source: wikipedia, accessed: 2019-09-28; Colourless crystals source: ICSC, accessed: 2019-09-04
  • I3

Products:

  • Na2S4O6
    • Names: Sodium tetrathionate source: wikidata, accessed: 2019-09-03
  • NaI
    • Names: Sodium iodide source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02, Sodium iodide (anhydrous) source: ICSC, accessed: 2019-09-04, NaI source: wikidata, accessed: 2019-09-02, Sodium monoiodide source: wikidata, accessed: 2019-09-02source: ICSC, accessed: 2019-09-04
    • Appearance: White solid | deliquescent source: wikipedia, accessed: 2019-09-27; Colourless-to-white hygroscopic crystals or white powder. turns brown on exposure to air source: ICSC, accessed: 2019-09-04
Warning: Unknown compound 'I3'